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Development and Validation of the Finite Element Model for the Human Lower Limb of Pedestrians 2000-01-SC22

An impact test procedure with a legform addressing lower limb
injuries in car-pedestrian accidents has been proposed by
EEVC/WG17. Although a high frequency of lower limb fractures is
observed in recent accident data, this test procedure assesses knee
injuries with a focus on trauma to the ligamentous structures.

The goal of this study is to establish a methodology to
understand injury mechanisms of both ligamentous damages and bone
fractures in car-pedestrian accidents. A finite element (FE) model
of the human lower limb was developed using PAM-CRASH™. The
commercially available H-Dummy™ lower limb model developed by
Nihon ESI for a seated position was modified to represent the
standing posture of pedestrians. Mechanical properties for both
bony structures and knee ligaments were determined from our
extensive literature survey, and were carefully implemented in the
model considering their strain rate dependency in order to simulate
the dynamic response of the lower limb accurately. The element
elimination option in PAM-CRASH™ was used to simulate both bone
fractures and ligamentous ruptures. Bone models were validated
against test results obtained from literature in both static and
dynamic conditions. The dynamic response of the knee joint was
validated against the response corridors from a series of
experiments with Post-Mortem Human Subject (PMHS) presented in the
literature. In addition, the lower limb model was validated against
published experiments with isolated lower limbs subjected less
motorized countries. The lower limb is one of the most frequently
injured body region in severe injuries to pedestrians mainly due to
direct impact from a vehicle front. According to the Pedestrian
Crash Data Study (PCDS) database by NHTSA, lower limb injuries are
the second most frequent region accounting for 26% of all AIS3+
injuries in pedestrians. Lower limb injuries are also very costly
and often lead to long-term disability or impairment.

The validated FE lower limb model was integrated with an upper
body model with rigid segments to obtain a full-body pedestrian
model. Computer simulations using both the pedestrian model and a
FE model for the car front were conducted to reconstruct a
published car-pedestrian impact test with PMHS. Leg fracture
observed in the experiment was reproduced from the FE car-
pedestrian model. The developed FE model can be used as an
effective tool to investigate injury mechanisms of the lower limb
in car-pedestrian accidents.